GSTR1 Return

file gstr1 for July separate
August and September ka ek sath in the month of September

If you put the details of all, it should be show, take time & click on generate gstr 1 summary repeatedly..

if you put details of all invoice & submit the same , it should be shown , take time & click on generate gstr 1 summary repeatedly..

I am trying to submit GSTR1 of July, August and September, in the month of September but when I am trying to add July month invoices, it is not accepting July month invoices..... furthermore there are no option available separately for the month of July GSTR1......if I check gstr return of July then it's showing option only for GSTR3b... which I have already filled.....any solution..??